japanese stuff    
Tokyo station
More well-known places:
Akihabara - All types of cheap (relatively for Japan) and interesting electronics can be found in the nearby electric town.
Asakusa - Famous old gate and group of temples.
Ginza - The place for the high end shopping and dining.
Harajuku - Young hang out area with a nice park nearby
Roppongi - Well-known for its nightlife catering to foreigners and clubs that stay open until morning.
Shibuya - Trendy area for younger Japanese. The famous crosswalk that appears in many movies of Japan is also here.
Shinjuku - A main business area, the station here is the busiest in the world.
Tokyo - Central station where Shinkansen high speed trains come and go from. The Imperial Palace where the emperor lives is nearby.
Ueno - A nice park and the best zoo in Japan.
Lesser known places:
Kappabashi - Otherwise known as Kitchen Town, you can find all sorts of kitchen supplies and a wide range of plastic food.
Tsukiji - Large open fish market